Transport system

ABSTRACT

A transport system includes at least one product carrier which is adapted to be moved along a slide way by means of a linear motor drive unit comprising a primary part and a secondary part. In order to improve the transport system in such a way that basically any number of product carriers can be moved along the slide way independently of one another and can be used in a versatile manner for transporting a great variety of products or workpieces, the product carrier is provided with a substantially flat base plate for transporting objects, the base plate having associated therewith the primary part, and the slide way having associated therewith the secondary part.

[0001] This application claims priority from German Patent ApplicationNo. 299 08 094.3, which was filed on May 6, 1999 and PCT Application No.PCT/EP00/04066, which was filed on May 5, 2000.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a transport system including atleast one product carrier which is adapted to be moved along a slide wayby means of a linear motor drive unit comprising a primary part and asecondary part.

[0003] Such a transport system is known from DE 4413625A1. In the caseof this known transport system a carriage means, used as a productcarrier, is moved along a first slide way by means of a linear motordrive unit and is displaceable together with said first slide way alonga second slide way. The first slide way has arranged thereon a stator orprimary part of the linear motor drive unit. A complementary rotor orsecondary part is secured to the carriage means. The carriage meanssupports a vertically displaceable support column, a product orworkpiece carrier in the form of a gripper being arranged at the at thelower end of said support column.

[0004] The known transport system serves to take hold of and lay down aspecific product or workpiece by means of the gripper. The carriagemeans is movable to a limited extent along the first slide way betweentwo fixed points, and the carriage means, together with said first slideway, is movable as a whole along the second slide way between twofurther points so that the articles held by the gripper can, on thewhole, be moved along each of the three coordinate axes alongthree-dimensional path curves.

[0005] The known transport system is disadvantageous insofar as onlyspecial articles, goods, workpieces or products can be transported dueto the gripper and insofar as only one product carrier can be moved byexternal influence via the primary part of the linear motor drive unit.

[0006] It is therefore the object of the subject matter of theapplication to improve the transport system described at the start insuch a way that basically any number of product carriers can be movedalong the slide way independently of one another and can be used in aversatile manner for transporting a great variety of products orworkpieces.

[0007] In connection with the features of the generic clause of claim 1,this object is achieved in that the product carrier is provided with asubstantially flat base plate for transporting objects, the base platehaving associated therewith the primary part and the slide way havingassociated therewith the secondary part.

[0008] A transport system having a similar structural design isdescribed in DE 298 16 285 of the same applicant; in this transportsystem, the secondary part is arranged on the product carrier and theprimary part is arranged on the slide way.

[0009] In comparison with the last-mentioned prior art and, similarly,also in comparison with the first-mentioned prior art, the presentinvention is so conceived that the linear motor is used in the reversemode so that each product carrier can be controlled individually andindependently of other product carriers. Each product carrier cantherefore be accelerated or delayed separately so that buffering of theindividual product carriers can be dispensed with e.g. along pathlengths where a congestion of product carriers may occur. An individualand conflict-free control of the various product carriers is obtained,and it will not be necessary to provide stoppers and/or shock absorberson the product carriers. In addition, a smaller number of productcarriers is required, since only as many product carriers are requiredas there are work orders to be executed along the slide way and the workstations located at said slide way. In comparison with the transportsystem according to DE 298 16 285, it can be assumed that the number ofproduct carriers required for a production process can be reduced by50%.

[0010] Due to the separate control of the individual product carriers,said product carriers can be accelerated and delayed more effectively,whereby the feed/discharge cycle times will be reduced and productiondowntimes can be made up for by variable speeds of the product carriers.

[0011] In view of the individual control of each product carrier, saidproduct carriers are protected against running into the back of otherproduct carriers, i.e. they are protected against colliding with otherproduct carriers, so that squeezing and shearing points on the productcarrier will be avoided. Such squeezing and shearing points mayotherwise occur when two successive product carriers collide or when aproduct carrier gets stuck in its slide way and when e.g. a subsequentproduct carrier runs into the back of said stuck product carrier.

[0012] According to a simple embodiment of the transport systemaccording to the present invention, the primary part can be arranged onthe base plate, especially on the lower surface of said base plate. Thismeans that such a primary part can be arranged in a simple manner andthat it will easily be accessible when maintenance work or the like hasto be carried out. In addition, the secondary part can be arranged indirectly opposed relationship with the primary part on the slide way,only a small gap remaining between these two parts.

[0013] In cases in which the base plate of the product carrier issufficiently high, the primary part can additionally be arranged in thebase plate such that it is at least partially embedded therein. If thebase plate is sufficiently high, the primary part can also be embeddedcompletely therein and terminate such that its lower surface is flushwith the lower surface of the base plate. The product carrier can inthis way be arranged very close to the slide ways, when e.g. also thesecondary part is arranged in an embedded mode of arrangement, so thatthe total construction height of the transport system can be reduced. Inaddition, the primary and the secondary part are largely protectedagainst damage in this way.

[0014] The linear motor drive unit can be implemented as an asynchronousmotor or a synchronous motor. The motor used is preferably anasynchronous motor.

[0015] Since the primary part is associated with the product carrier orbase plate, a suitable voltage or power supply must be provided.According to one embodiment, a voltage supply unit extends along theslide way and is especially arranged on this slide way and the productcarrier is in contact with the voltage supply unit via a sliding-contactmeans. Such voltage and power supply means for moving objects can berealized in many different ways and a great variety of realizations areknown in practice. In the case of the transport system according to thepresent invention, the voltage supply unit can be implemented e.g. as aconductor rail along which a sliding contact projecting from the productcarrier can be moved.

[0016] The slide way of the transport system according to the presentinvention can be realized in different ways. DE 298 16 285, which isowned by the same applicant, describes e.g. horizontally and verticallyarranged slide ways with suitable guide means for the product carriers.The base plates are oriented horizontally or vertically in acorresponding manner. Such horizontal and vertical arrangements withsuitable holders and guide means according to DE 298 16 285 can also beused in the transport system according to the present invention.

[0017] In the described embodiment of the transport system according tothe present invention, the slide ways are formed by a pair of sliderails held in spaced relationship with one another by a plurality ofsupport sections set up substantially vertically on a foundation.Instead of the support sections, it is also possible to use, in asimilar way, support posts having a structural design which is similarto that described in DE 298 16 285.

[0018] In order to bridge the free space between the support sections, acover section can be arranged between the support sections. This coversection can extend along the slide ways in the whole transport system.

[0019] Since the cover section faces substantially the lower surface ofthe base plate or product carrier, the secondary part or the secondaryparts can be arranged on the cover section along the slide way. In thecase of synchronous motors, magnets and especially profile magnets areused as secondary parts, which, analogously to the primary part, can bearranged on the cover section or which can be embedded at leastpartially in said cover section, whereas the secondary parts used in thecase of asynchronous motors are preferably copper rails with steelbacks.

[0020] The base plate can be guided along the slide way along itslongitudinal edges and/or on its lower surface adjacent saidlongitudinal edges so as to be able to move the product carrier reliablyalong the slide way.

[0021] This mode of guiding the base plate can be realized in differentways. Roller elements, spherical elements, guide elements,friction-reducing guide means or the like can, for example, be arrangedbetween the base plate and the slide way. These elements or means can bearranged in spaced relationship with one another or also in a continuousmode in the case of rail-shaped guide elements or guide means. Therespective elements or means can be provided on the slide way or sliderails and/or on the base plate.

[0022] Since the product carriers of the transport system according tothe present invention can be controlled individually, it will beadvantageous to monitor their position. Such position monitoring can berealized by arranging a position determination unit between the productcarrier and the slide way. This position determination unit may bedefined e.g. by a scale and a scale reading system. The scale can bearranged on the product carrier or on the cover section or on the slideways and, accordingly, the scale reading system can be arranged on therespective other part. Preferably, the scale reading system is arrangedon the moving product carrier so that the respective product-carrierposition can be determined by the product carrier itself.

[0023] Due to the exact position determination for each product carrier,an indexing means at each work station along the slide way can, forexample, be dispensed with as well, since each product carrier can bepositioned precisely relative to the scale. In this connection, it canadditionally be considered to be advantageous when the product carrieris provided with onboard electronics which communicate, especially viathe voltage supply unit, with a central station so as to exchange dataand/or instructions. In this way, it is not only power that istransmitted to the product carrier via the voltage supply unit, but alsoan exchange of information takes place between said product carrier andthe central station. This information can be transmitted e.g. fordetermining the position of the individual product carriers, foraccelerating or delaying said product carriers, for identifying them,for electrically encoding a work order or the like. In addition, theinformation can be transmitted by means of a bus system between theproduct carrier and e.g. the cover section. It will be advantageous toimplement such a bus system in optical waveguide technology.

[0024] The product carrier can be provided with display and/orinterrogation and/or input means so that information can also begathered from the work stations and from the product carriers directlyat said work stations or while said product carriers are moving. In thisway, information can be displayed directly at the product carrier e.g.via the display means. It is also possible to input via an input means afree-to-move information for the product carrier, which can betransmitted to the central station. The product carrier can be moved onimmediately after the free-to-move information, whereby absolutely freeline clocking for the whole transport system will be obtained.

[0025] The display means can also be used for transmitting informationto the workers at the various work stations or additional informationcan be called from the central station via a respective interrogationmeans and via the product carrier.

[0026] Especially in a transport system in which the base plate has tobe associated with a work station for a prolonged period of time, itwill be advantageous when substantially the base plate alone is leftbehind at this work station, whereas the product-carrier drive meansassociated with said base plate is used e.g. for other base plates. Thiscan be realized by arranging the primary part on a vehicle which isadapted to be coupled to the base plate. This vehicle is coupled to ordecoupled from the base plate according to requirements. One vehicle canbe used for moving a plurality of base plates so that the total cost ofthe transport system according to the present invention will be reduced.In this connection, it will also prove to be advantageous when anidentification can be associated with each product carrier or rather thebase plate thereof, so that the base plate can be transported to thelocation of use, or transported away after it has been used, by means ofan arbitrary vehicle. It is also possible to operate specific sectionsof the transport system with only one vehicle which moves all the baseplates that are movable along this transport section.

[0027] In order to be able to identify not only the position of the baseplate, it is in this connection considered to be advantageous when arespective position determination unit is associated with the base plateand with the vehicle.

[0028] In order to be able to move the vehicle independently of the baseplate and, if necessary, said base plate also independently of therespective vehicle, the vehicle can be movable along a separate vehicleslide way extending especially below the base plate.

[0029] In the most simple case, this vehicle slide way can be formed onthe cover section.

[0030] The voltage supply unit or a further voltage supply unit can bearranged along the vehicle slide way on the cover section, since thevehicle should be movable along the vehicle slide way also withouthaving the base plate coupled thereto.

[0031] According to one embodiment of the transport system according tothe present invention, the vehicle slide way can consist of asubstantially U-shaped slide-way groove which is open at the top in thedirection of the base plate and which is implemented in the coversection. In this groove the vehicle moves unhindered and independentlyof the base plates.

[0032] A simple coupling possibility between the vehicle and the baseplate can be realized e.g. by arranging a releasable coupling meansbetween the vehicle and the base plate. This coupling means may e.g. beprovided with a lifting magnet which, when the base plate is beingcoupled to the vehicle, can be displaced from the vehicle upwards into asuitable opening provided in the lower surface of the base plate. Forthe purpose of decoupling, the lifting magnet is drawn back.

[0033] Further coupling means are known in practice and can also be usedin the transport system according to the present invention in acorresponding manner. It is also possible to decouple e.g. the vehicleand the base plate by hand, when the base plate has reached a desiredposition. The arrangement of the product carrier at the desired positioncan take place e.g. via the input means for fine-positioning anddecoupling from the vehicle can subsequently also take place with theaid of this means. It is also possible to decouple the base plate fromthe vehicle automatically or by a mechanical stop or the like, when adesired target position has been reached.

[0034] The slide-way groove can be covered by a cover so as to prevent,as far as possible, workers from putting their hands into the travellingpath of the vehicle along the transport system, whereby the risk ofinjuries will be reduced, said cover having formed therein a slot whichextends in the direction of movement of the vehicle and which permitsthe coupling means to extend therethrough. This comparatively narrowslot will also prevent parts from falling onto the vehicle slide way,which parts would obstruct an advance movement of the vehicle or evencause damage to said vehicle.

[0035] An adjustable rotary plate can rotatably be supported on the baseplate so that products placed on the product carrier in the transportsystem according to the present invention can be oriented in accordancewith their intended use. The rotary plate may cover only part of thebase plate, but it may also have the same dimensions as or even largerdimensions than the base plate.

[0036] A linear rotary drive unit can be implemented between said rotaryplate and the base plate so as to be able to easily rotate the rotaryplate relative to the base plate. Like the drive means for the vehicleand the product carrier, also this linear rotary drive unit can besupplied via the above-described voltage supply unit.

[0037] In order to prevent especially the base plates which have beendecoupled from the vehicle from continuing their movement, a brake meanscan be arranged on the slide ways, on the cover means or on the baseplates. This brake means especially serves to stop and retain inposition the base plate in the in the area of work stations along theslide way. Also the brake means can be operated manually orautomatically.

[0038] Since the vehicle is movable in both directions along the slideway, it may prove to be advantageous, especially when a plurality ofvehicles move along one transport section, when the vehicle slide wayincludes at least one return section for returning vehicles, which havebeen decoupled from the base plate, to a return location. This willpermit one vehicle to be moved past another vehicle without hindrance.

[0039] Due to the separate control of the various product carriers, thetransport system according to the present invention offers thepossibility of accelerating and decelerating the product carriers moreeffectively, whereby the cycle time per work station will be reduced.The product carriers are also able to carry out a reverse movement sothat it will e.g. be possible to repeat a work order which has not beencarried out in a satisfactory manner. Furthermore, various, partiallyparallel production and transport paths can be implemented along aproduction line. An almost arbitrary routing without corner rotatingstations for changing the direction of movement of the product carriersis possible. Finally, it should also be pointed out that the transportsystem according to the present invention permits a simple adaptation ofheights so that the product carriers can also ascend and descend duringthe production process.

[0040] In the case of a further embodiment of the transport systemaccording to the present invention, the workpiece carrier or productcarrier may have arranged thereon a rotary plate which is adapted to berotated and/or displaced relative to the carrier. In addition, thisrotary/displacement plate may also have arranged thereon means forgripping and clamping the workpiece or the product in question, or itmay have arranged thereon a suitable reception means for the product.

[0041] The transport system according to the present invention providesthe possibility of linking with only one carrier a plurality ofassembly/processing locations along a production line and of changingpositions of the workpiece or of the product via the respectiverotary/displacement unit especially also while the transport is takingplace.

[0042] With respect to DE 298 16 285 of the same applicant, it should bepointed out that the above-described vehicle including a coupling meansfor a base plate may also be implemented in the way described in said DE298 16 285, i.e. such that the secondary part is arranged on the vehicleand the primary part on the slide way or the like. The above-describedadvantages for the primary part on the moved object of the transportsystem are, however, not achieved in this case.

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In the following, advantageous embodiments of the presentinvention will be explained in detail making reference to the figuresadded in the drawing, in which:

[0044]FIG. 1 shows a section along line I-I through a transport systemaccording to the present invention as shown in FIG. 3.

[0045]FIG. 2 shows a section through a second embodiment correspondingto the section of FIG. 1.

[0046]FIG. 3 shows a top view of a transport section of a schematicallyshown transport system according to the present invention.

DETAIL DESCRIPTION

[0047] In FIG. 3 it can be seen that the transport system 1 includes aslide way 2 extending e.g. along a production line so as to transportworkpieces, products or other objects by means of a product carrier 6.The product carrier 6 has a substantially flat surface onto which therespective object can be placed and then transported in directions 34along the slide way 2. The product carrier 6 is guided along thelongitudinal sides thereof by slide rails 13 which define the slide way2 and between which a cover section 14 extends.

[0048]FIG. 1 shows a section along line I-I of FIG. 3. In this figureand also in the following figure identical components are designated byidentical reference numerals, only part of the respective componentsbeing mentioned.

[0049] The product carrier 6 is essentially defined by a base plate 7having horizontal upper and lower surfaces. A product, workpiece orother object can be placed on the upper surface of the base plate 7.

[0050] Along lateral edges 15, 16 of the base plate 7 and in areas ofthe lower surface 8 which are located adjacent the lateral edges, thebase plate 7 is guided by roller and guide elements 17, 18 along theslide rails 13. The slide rails have a substantially L-shapedcross-section, each leg of the L having associated therewith a rollerand guide element 17, 18. In the area of the lateral edges 15, 16 andlower surface 8, the base plate 7 is provided with slide strips 32 onwhich the respective elements 17, 18 abut.

[0051] The base plate 7 has arranged therein a primary part 3 whichconstitutes part of a linear motor drive unit 5. A secondary part 4 ofthe linear motor drive unit 5 is arranged in opposed relationship withsaid primary part 3, said secondary part 4 being arranged in a coversection 14 extending between substantially vertical support sections 12.The secondary part 4 is defined e.g. by profile magnets in the case ofsynchronous motors and by copper rails with steel plates in the case ofasynchronous motors along the slide way 2, cf. FIG. 3.

[0052] For supplying power to the primary part 3, a sliding-contactmeans 10 projects from the lower surface 8 of the base plate 7approximately at the center of said lower surface 8. Thissliding-contact means engages conductor rails 11 of a voltage supplyunit 9. The sliding-contact means 10 extends through a slot 35 in thecover section 14 in the direction of said voltage supply unit 9.

[0053] For determining the position of the product carrier 6, a positiondetermination unit 19 is provided, which comprises a scale means 29 anda scale reading means 30. The scale means 29 is arranged on an uppersurface of the cover section 14, which is opposed to the lower surface 8of the base plate 7, and extends parallel to the slide rails 13. Thelower surface 8 of the base plate 7 has arranged thereon the scalereading means 30 which is located in opposed relationship with the scalemeans 29. A bus system consisting of bus lines 35 is arranged inside-by-side relationship with the position determination unit 19, saidbus lines being implemented e.g. in optical waveguide technology.

[0054]FIG. 2 shows a section, analogous to FIG. 1, through a secondembodiment. This second embodiment differs from the first one insofar asa vehicle 20, which is adapted to be coupled to the base plate 7, isprovided. Furthermore, a rotary plate 26 is shown in the form of brokenlines on the upper surface of the base plate 7 in FIG. 2, said rotaryplate 26 being supported on the base plate 7 such that it is adapted tobe rotated relative thereto. The rotary plate 26 is provided with alinear rotary drive unit 27 as a rotary drive.

[0055] The cover section 14 has arranged therein a U-shaped slide-waygroove 22 for accommodating the vehicle 20. The vehicle 20 isaccommodated almost completely in this slide-way groove 22. On a lowersurface of the vehicle, which is opposed to the base plate 7, saidvehicle 20 is movable along a rail 33 comprising a vehicle slide way 21.The primary part 3 is integrated in the vehicle 20 as part of the linearmotor drive unit 5. The complementary secondary part 4 is located withinthe slide-way groove 22 in closely spaced relationship with the primarypart 3. The voltage supply unit 9 including the conductor rail 11 isarranged in the slide-way groove 22 in opposed relationship with thesecondary part 4. The sliding-contact means 10 projecting from thevehicle 20 is in engagement with this conductor rail 11.

[0056] For determining the position of the vehicle, a respectiveposition determination unit 19 is provided between the vehicle 20 andthe slide-way groove 22. Like the position determination unit 19 whichhas already been described in FIG. 1, this position determination unit19 can be composed of a scale means 29 and a scale reading means 30. Abus system 35 can be provided as well.

[0057] The respective position determination unit 19 for the base plate7 itself is not shown in FIG. 2 so as to simplify matters.

[0058] For covering the slide-way groove 22, a cover 24 is arrangedbetween the cover section 14 and the lower surface 8 of the base plate7, said cover 24 resting on the top surface of the cover section 14 andbeing releasably secured e.g. to this cover section 14.

[0059] The cover 24 is provided with a slot 25 above the vehicle 20,said slot 25 extending in the direction of movement of the vehicle 20. Acoupling means 23 extends through said slot 25 in the direction of thebase plate 7.

[0060] In the embodiment shown, the coupling means 23 is defined by alifting magnet which is adapted to be automatically raised and loweredin the directions 31. From the vehicle 20, this lifting magnet can beinserted into and removed from a cavity provided in the lower surface 8of the base plate 7.

[0061] Reference is again made to the fact that, in the transport systemaccording to the present invention, it is possible to guide the productcarriers 6 vertically, as has been described e.g. in DE 298 16 285 ofthe same applicant. For adapting the transport system described in thepresent connection to such vertical guidance, the features described inthe above-mentioned Utility Model can also be adopted for the presentapplication.

What is claimed is:
 1. A transport system including at least one productcarrier which is adapted to be moved along a slide way by means of alinear motor drive unit comprising: a primary part; a secondary part;wherein the product carrier is provided with a substantially flat baseplate for transporting objects; the base plate having associatedtherewith the primary part; the slide way having associated therewiththe secondary part; said product carrier being provided with onboardelectronics which communicate via a voltage supply unit with a centralstation so as to exchange data and/or instructions; said voltage supplyunit extending along the slide way and being arranged on said slide way;and said product carrier being in contact with the voltage supply unitvia a sliding-contact means.
 2. A transport system according to claim 1wherein the primary part is arranged on a lower surface of said baseplate.
 3. A transport system according to claim 1 wherein the primarypart is arranged in the base plate such that it is at least partiallyembedded therein.
 4. A transport system according to claim 1 wherein thelinear motor drive unit is a synchronous motor.
 5. A transport systemaccording to claim 1 wherein the voltage supply unit is implemented as aconductor rail.
 6. A transport system according to claim 1 wherein theslide way is formed by a pair of slide rails held in spaced relationshipwith one another by a plurality of support sections set up substantiallyvertically on a foundation.
 7. A transport system according to claim 6wherein a cover section is arranged between the support sections.
 8. Atransport system according to claim 7 wherein the secondary part isarranged on the cover section along the slide way.
 9. A transport systemaccording to claim 6 wherein the base plate is guided along the sliderails along its longitudinal edges.
 10. A transport system according toclaim 6 wherein the base plate has longitudinal edges and wherein saidbase plate is guided along the slide rails along its lower surfaceadjacent said longitudinal edges.
 11. A transport system according toclaim 1 wherein elements are arranged between said base plate and theslide way for guiding the base plate; said elements selected from thegroup consisting of roller elements, spherical elements, guide elements,and friction-reducing means.
 12. A transport system according to claim 1further comprising a position determination unit arranged between theproduct carrier and the slide way.
 13. A transport system according toclaim 7 wherein bus lines are arranged on the product carrier so as toexchange data and/or instructions with the cover section.
 14. Atransport system according to claim 1 wherein the product carrier isprovided with display means.
 15. A transport system according to claim 1wherein the product carrier is provided with input means.
 16. Atransport system according to claim 1 wherein the product carrier isprovided with interrogation means.
 17. A transport system according toclaim 6 wherein the primary part is arranged on a vehicle which isadapted to be coupled to the base plate.
 18. A transport systemaccording to claim 17 wherein the vehicle is adapted to be moved along aseparate vehicle slide way extending below the base plate.
 19. Atransport system according to claim 18 wherein the vehicle slide way isformed in the cover section.
 20. A transport system according to claim18 wherein the voltage supply unit is arranged along the vehicle slideway on the cover section.
 21. A transport system according to claim 20,wherein the vehicle slide way is implemented in the cover section as asubstantially U-shaped slide-way groove which is open at the top in thedirection of the base plate.
 22. A transport system according to claim17 wherein a releasable coupling means is arranged between the vehicleand the base plate.
 23. A transport system according to claim 21 whereinthe slide-way groove is adapted to be covered by a cover having formedtherein a slot which extends in the direction of movement of the vehicleand which permits the coupling means to extend therethrough.
 24. Atransport system according to claim 1 further including an adjustablerotary plate rotatably supported on the base plate.
 25. A transportsystem according to claim 24 further including a linear rotary driveunit for rotating the rotary plate disposed between said rotary plateand the base plate.
 26. A transport system according to claim 1 furtherincluding a brake means for the product carrier arranged on said slideway at least in the area of work stations along the slide way.
 27. Atransport system according to claim 18 wherein the vehicle slide wayincludes at least one return section for returning vehicles, which havebeen decoupled from the base plate, to a return location.